1. Field of the Invention
The present invention relates to a method for manufacturing a liquid jet head that discharges a desired liquid by means of bubbles created by causing thermal energy to act upon liquid. The invention also relates to a liquid jet head, a head cartridge that uses the liquid jet head, and a liquid jet recording apparatus as well.
The present invention is applicable to a printer that records on a recording medium, such as papers, threads, textiles, cloths, leathers, metals, plastics, glass, wood, ceramics, and also, applicable to a copying machine, a facsimile equipment provided with communication system, and a word processor provided with the printing unit, among some others. Further, the invention is applicable to recording systems for industrial use which are structured by the complex combination of various kinds of processing apparatuses.
Here, the term xe2x80x9crecordingxe2x80x9d referred to in the specification hereof means not only the provision of meaningful images, such as characters, graphics, but also, it means the provision of such meaningless images as patterns recorded on a recording medium.
2. Related Background Art
There has been known conventionally the so-called bubble jet recording method, that is, an ink jet recording method, in which by the application of thermal energy or the like to ink, the change of its states is made with the abrupt voluminal changes (creation of bubbles) to follow, and then, by the acting force brought about by this change of states, ink is discharged from each of the discharge ports, and allowed to adhere to a recording medium for the formation of images. A recording apparatus that uses this bubble jet recording method is generally provided with the discharge ports for discharging ink; the ink flow paths communicated with the discharges ports; and heat generating elements (electrothermal transducing devices) that serve as energy generating means for discharging ink which has been distributed into each of the ink flow paths as disclosed in the specifications of Japanese Patent Publication 61-59911 and Japanese Patent Publication 61-59914.
With the recording method described above, it is possible to record high quality images at higher speed with a lesser amount of noises, and at the same time, it becomes possible to arrange the discharge ports for discharging ink in high density for the head that implements this recording method. Therefore, this method has such excellent advantages as to enable images to be recorded in higher resolutions with a smaller apparatus, and also, images to be recorded in colors easily, among many other advantages. With these advantages, the bubble jet recording method has been widely adopted in recent years for a printer, a copying machine, a facsimile equipment, and many other office equipment. This method is even utilized for a textile printing system and some other industrial systems.
On the other hand, the conventional bubble jet recording method may sometimes bring about the creation of accumulated substance due to burning of ink on the surface of the heat generating elements, because heating is repeated while the heat generating elements are in contact with ink. Also, in such a case where the liquid for discharge use tends to be easily deteriorated by the application of heat or the liquid has a property that it does not provide a sufficient bubbling easily, the bubble formation by the direct heating for discharges by use of the heat generating elements described above does not present good condition in some cases.
In this respect, the applicant hereof has proposed a method in which the discharge liquid is discharged by bubbling the bubbling liquid by the application of thermal energy through the flexible film that separates the bubbling liquid and discharging liquid as disclosed in Japanese Patent Laid-Open Application 55-81172. The structure of this method formed by use of the flexible film and the bubbling liquid is such that the flexible film is provided for a part of each nozzle. In the same respect, there has been disclosed a structure in the specification of Japanese Patent Laid-Open Application 59-26270 that uses a large film for the separation of the entire head into the upper and lower parts. This large film is provided for the purpose to prevent liquid in each of the two liquid paths from being mixed by being pinched by the two plate members that form the liquid paths.
On the other hand, there has been a disclosure such as in the specification of Japanese Patent Laid-Open Application 05-229122 wherein the bubbling liquid itself has a specific property in consideration of the bubbling characteristics such as to present a lower boiling point than that of the discharging liquid or such as in the specification of Japanese Patent Laid-Open Application 04-329148 wherein a liquid having electric conductivity is used as bubbling liquid.
Here, the present inventors have proposed a liquid jet head which is capable of maintaining liquid discharges at a higher level, at the same time, producing the effect of separating function provided by the separation film to be used.
Such liquid jet head comprises a first liquid flow path for use of discharging liquid, which is communicated with each of the discharge ports; a second flow path that includes each of the bubble generating areas, while being arranged to supply bubbling liquid or to make it movable; and each of movable separation films to separate the first and second flow paths, having a recessed portion that faces the bubble generating area, respectively.
For the liquid jet head described above, it is effective for the stabilized discharges thereof to adopt a highly polymerized material that has a good response to bubbling as the movable separation film.
However, when a highly polymerized material is used, the balance between the sagging amount of the film and the bubbling power may exert influence on the discharge stability. In other words, if the bubbling power is stronger than the sagging amount of the film, power of the bubbling power is transformed into the energy that acts upon the expansion of the film, thus making the adjustment of such balance extremely sensitive.
Now, therefore, the inventors hereof have studied to develop a liquid jet head which is capable of maintaining the liquid discharges at a higher level, but not spoiling the effectiveness of the liquid jet head described above, as well as a method for manufacturing such liquid jet head.
During the studies of the inventions hereof, the present invention is designed, which is aimed at the provision of an epoch-making liquid jet head capable of enhancing the discharge efficiency of liquid droplet discharges, at the same time stabilizing and improving the volume of each discharged liquid droplet or the discharge speed thereof, and the method for manufacturing such liquid jet head as well.
It is an object of the invention to provide a liquid jet head which comprises at least first liquid flow paths communicated with discharge ports for discharging discharge liquid; second liquid flow paths having bubble generating areas for creating bubbles in bubbling liquid; and a movable separation film for essentially separating the first liquid flow paths and the corresponding second liquid flow paths from each other at all times, and for this liquid jet head, the stabilization of the discharges is attempted by making the displacement of such movable separation film constant all the time. The object of the invention is to provide the method for manufacturing such liquid jet head.
It is another object of the invention to provide a liquid jet head capable of essentially separating discharge liquid and bubbling liquid from each other at all the time by use of a movable separation film, and also capable of performing the stabilized discharges at all the time by displacing the movable separation film by the application of force exerted by the bubbling pressure, and to provide the method for manufacturing such liquid jet head as well.
In order to achiever these objects, the method of the present invention for manufacturing a liquid jet head which is provided with first liquid flow paths communicated with discharge ports for discharging discharge liquid, second liquid flow paths having heat generating elements for creating bubbles in bubbling liquid, corresponding to the first liquid flow paths, and a movable separation film for essentially separating the first liquid flow paths and the corresponding second liquid flow paths from each other at all times, comprising a first step of forming organic film becoming the movable separation film, and a second step of providing permanent distortion for the organic film formed in the first step.
In the aforesaid second step, stress beyond yielding point is provided for the movable separation film. It is preferable to contain polyparaxylene in the movable separation film.
With the structure as described above, permanent distortion is provided for a desired movable separation film after the movable separation film is formed to essentially separate the first liquid flow paths and the second liquid flow paths. Then, most of the elasticity of the movable separation film is eliminated (that is, the movable separation film is plastically deformed) so that part of the bubbling power is not allowed to be transformed into the energy that causes the film to stretch. As a result, for the desired movable separation film in the plastic region, the displacement of the film becomes greater to the extent that part of the bubbling power is not allowed to be transformed into the energy that causes the film to stretch as compared with the case where the same power is applied to the other movable separation film in the elastic region. Therefore, the discharge liquid droplets are made larger dots. In other words, with respect to the desired movable separation film, it is possible to change the discharging droplet into a larger one with the application of the same bubbling power applied to the smaller one in accordance with the present invention. Here, with the additional process of the distortion of the present invention, there is no need for adjusting the bubbling power when it is desired to shoot larger dots and smaller dots locally from the multiple nozzle head or it is desired to adjust the amount of discharging liquid droplets largely in order to discharge them in a specific amount without fluctuation. Since a head of the kind can discharge larger dots without increasing the bubbling power, the dissipation power can be reduced, hence leading to making the life of the head significantly longer.
Also, the present invention includes the inventions based upon the new recognition of the subjects as to the organic film used as the material for the aforesaid separation film, which will be readily understandable from the description of the embodiments to follow.
In this respect, the terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d referred to in the description of the invention hereof are related to the flow direction of the liquid toward the discharge ports from the supply source of the liquid through the bubble generating areas (or movable members) or meant to indicate the directions related to the structure thereof.